A circuit switched (CS) network is a wireless network that provides a circuit switched domain service such as a voice call. A 2nd Generation/3rd Generation 2G/3G) network such as GSM and WCDMA has a wide coverage. Meanwhile, with development of network technologies, a packet switched (PS) network specially providing a data service, for example, a Long Term Evolution (LTE) network, is also deployed on a large scale. Therefore, in a current communications network, the CS network and the PS network coexist, and an operator may provide a circuit switched domain service for a user by using the 2G/3G network and provide a data service for the user by using the LTE network.
Based on the network coverage manner, a 3rd Generation Partnership Project (3GPP) organization puts forward a “circuit switched fallback” (CS Fallback, CSFB) technology, so that when needing to process a CS service, user equipment (UE) that is registered in an LTE network falls back to a CS domain of a 2G/3G network to complete service processing. After the CS service is completed, an existing protocol further defines a CSFB fallback mechanism, so as to ensure that after completing the CS service, the UE can return to the PS network to perform a PS service. The CSFB fallback mechanism specifically includes: a mobile switching center (MSC)/visitor location register (VLR) releases a connection established for the CS service, and indicates to a base station that the current connection is established for CSFB. When releasing the connection, the base station instructs the UE to obtain LTE frequency band (Frequency) information of the LTE network by reselecting, so that after redirected to a suitable cell supporting the LTE frequency band information, the UE randomly selects an available LTE public land mobile network (PLMN) in broadcast information of the suitable cell.
In a process of implementing the foregoing fallback to the LTE network, the inventor finds that the prior art has at least the following problems: A data service suspended in an LTE PLMN in which registration is performed before CSFB is triggered cannot be restored, which results in termination of an on-going data service and unnecessary inter-PLMN handover, and affects service experience of a user.